Electric-circuit protector.



PATENTED DEC. 25, 1906.

C. A. ROLEE.

ELECTRIC CIRCUIT PROTECTOR.

AIPLICATION FILED DEC. 3. 1900.

UNITED STATESr PATENT OFFICE.

CHARLES A. ROLFE, O F-CHICAGO, lLlJlNOlS, ASSIGNOR, BYMESNE -ASSIGNMENTS, TO ROLFE ELECTRIC CO., OFROCHESTER, NEW

YORK, A CORPORATION OFNEW YORK.

ELECTRIC-CIRCUET PROTECTOR.

No. $323,513. speeication of Application led December To all whom/ #burg/concern: l p

Be it known that I, CHARLES A. RoLFn, a citizen of the l United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement iin Electric-Circuit Protectors, (Case 4,) of which the following is a full,

f clear, concise, and eXact description, reference being had to the accompanying drawings, forming a part ofthis specification.

My invention relates to protectors for protecting low-tension instruments and circuits from injury by the intrusion of unduly strong currents, such as power and lighting currents.

The invention relates in particular to a variety of such electrical protectors in which is employed a body or mass of material which may be said to be softenable or fusible-that is to say, suilciently responsive or susceptible lto a moderate degree of heat to causel it to be softened or fused by the application of suoli an amount of heat. In certain forms of this style'of protector the fusible or softenable material consists of wax. ln others it consists of solder. Various kinds of wax have been employed, as have also various kinds of solder, the composition of each being suiiiciently'varied to cause them to be properly responsiveto heat of any desired 1.noderate degree and enduring f'or any desired moderatelength of time. In these protectors the operation of the device is pern'iitted by the fusingor softening of the mass or body `of f-u'sible o r softer'iable material, and to suchend the device S.. aie each provided with a de'vice for concentrating heat,.so that .it Shall be applied to the 'said mass orbodyof n aterial and also 'with a circuit-.Controlling -,device or set of devices by which the circuit lis controlled in any desired way by the f u'sion or softening of'said bodyo f material,`

The heatconcentiarting devices and tne' circuit-controlling 'devl'ceshave varied ver' largely indifferent frns df protectors. 'In

most instances the heat-concentrating'devlc has consisted"f a coil offlne wire which. would become heated, and soform a heated. mass or ball'upon the I[flassauge of an unduly" strong current through the wire. Tlg'i'is coil of iine'wire has vbeen so associated with' the niass or body of'fusible orv :softenable mate- Letters Patent. Patented Dec. 25, 1906.

3,1900. Serial No. 38.437.

rial that when the coil has become heated by of fusible or softenable material has been fused or softened. In certain of such devices the 'heat-concentrating coil has been embedded within the mass or body of material, while in others the coil has been arranged outside of or surrounding the said mass or body. In either case, however, the association has been so close that thel generation of a moderate degree of heat in the coil has affected the mass or body of fusible or softenable material. 1

rl`he circuit-controlling devices have usually consisted of suitable mechanisms by ing or fusing of the fusible or ksoftenable material, although in certain instances these circause the circuit to be shunted to ground instead of .being opened. In either case the arrangement is such that'when an unduly strong current traverses the heat-concentrating device and causes the generation of a sufficient amount of heat"l to affect the mass or body'of fusible or softenable material the circuit-controlling device operates. AIn the one case the circuit is opened and inthe other lthe instrument o njthe circuit and the' clrcult vitself are protected from the unduly strong current-in the first instance the complete stoppage ofthe currentand'in the second by its .diversionffroni the circuit and instrumellilnder protection to another circuit.'

trated', and claimed in the `patent to Albert Bar-league. 445,217, 0f January' y27, i891, forv a thermal cut-out, heat-susceptible device consists of la ball or buttonof wax, and the heat-concentrating massv con'sistsof 'a' coil of wire, which isernbedded within the material of the wax. The ycoifof wire surrounds the end cfa loop or shank, and a' spring is arranged and held under tension by this loopor shank. The ball or button of'wax is. held lagainst the op eration of the spring by a's'uitable support-or abutment. The operation of 'the device,

intrudesu on the line the coil of Wire enerwhich the circuit is opened upon the softencuit-controlling devices'have been such as to Asan example of a protector of the class meutioned'` might cite that described, illusl'In this patent the then, Ais that when an unduly stro1 1g current the unduly strong current the body or mass case it is shunted to ground. lIn b'ot'hv'cases| reo 'forming a coil of the same, and thus self-1ncurrents.

ates sufficient heat to cause the portion of the wax ball or button immediately surrounding it to soften. Thespring is thereby released and operates so as to withrdaw the end of the loop, With the coil surrounding it, from the interior of the ball or button of wax. By such withdrawal and by the continued movement of the coil and loop as they are acted upon by the spring the ends of the coil are ruptured, so as to break or open the circuit.

The invention of the present application relates in particular to the heat-concentrating device by. which the heat-susceptible body or mass is affected; and its object is to rprovide the'simplestpossib'le and least expensive form'of device of thiskind and at the same time 4to dispense entirely with the use of condiicting-wires for such device and the attendant inconveniences thereof.

In 'carryingy outmy ypresent invention I employ zas ahem-concentrating device a conductor having a high specific resistance.

The substance now most suitable, so far as I.

am at present aware, is 'high-resistance graphite-such, for example, asis atpresent' employed. in ordinary :lead-pencils. This substance'has'avery high speclfic resistance,

so that themere passage of even moderate currents through it results 1n itsfbeing rapidly heated'thr'ough its owninternal `resist-- ance, the -connections to'it, 'it being'understood, beinggood, so th'atthe'only effective resistance is the -internal resistance 'of the gra hite. By actual experimentation` have found th'atia's'hort length of graphite ofthis kindf'will Generate sufii'cient heat to operate the protec' ,or upon the plassage ofvery small In fact, by t e use of graphiteiin this'way the device can'be made 'as -sensitive andas accurate and'reliable in operation 'als could heretofore bedone withfa' coil of fine wire. By theiseof'such a material ofhigh specific resistance suflicient heat canl be secured in a short`rod or stick thereof without duction isavoided and a protective device with `a non-inductive resistance is provided. At the same time the expense of manufacture isl greatly reduced, and the' device' is sim ler. This non-'metallic subst'ance, such as car on,

can'be combined or associated or united with I do not desire to be ylimited to them in the broader feature of the invention, lfor I consider that this broader feature can be ernbodied in anyA style or form of protector which is now or may hereafter be constructed.

In the accompanying drawings, Figure 1 is a side elevation of a protector embodying .my present invention, the said protector being in general arrangement that referred to as shown and described in my said applications, Serial Nos. 618,795 and 618,796. Fig. ,2 is an end elevation ofthe same. Fig. 3 is a vertical section of a structure in which the heat concentrating and heat susceptible masses or bodies are associated as used in the protector shown in Figs. 1 and 2. Figs. 4 and 5 are views corresponding to Figs. 1 and 2 of a modified form of protector embodying my`invention,this protector being in general this protector comprises an insulating-base' A'a'nd a pair'of circuit-breaking devices 'B B. Theptwo circuitbreaking devices B 'B are intended for the opposite sides of the circuit to'be protected. For their accommodation the base 'A is provided with two pairs of sockets 1 '1'which are connected 'with suitable terminal'wires 2 2, 'whereby eachV of the circuit-breaking' devices'B B' can be included inthe circuit.

The devices BIB are desirably exactly'the 'same in construction, so that a description of one of them will Vanswerfor both. :Each one comprises a Apair of metal Yrods 3 3, whose lower ends are 'adapted to fit into'the sockets 1 l1 of the'bas'e A; a top cross'epiece 4,'rigidly 'secured'to the upper ends of'therods '3 3; a

lower cross-piece 5, which is arranged loosely 'upon'the lower'portions'of the rods 3 3; a -pair 'of coiled springs' 6, which inclosethe portion'of the rods 3'3 between the'cross- `pieces 4 and 5 :and tend normally to separate said 'cross-pieces fromV one another. The springs 6 6 are held'in tension,'or, in other words, the cross-pieces 4 and 5 fare held a ainst separation by` a hook or link 7, w .ich is secured to the lower crossiece 5, and 'a releasing device C, Fig. 3, w ich includes' in its' construction the heat generating or concentrating andthe heat-susceptible devices. The device C illustrated lconsists of an outer metallic 'shell 8 andan inner metallic shell 9, whose lower end is embedded or "inclosed withintheouter shell`8 and whose Aupper 'end is expanded or flared, so as to be appreciably larger than the'outer shell 8.

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The lower portions of the inner shell 9 and .the outer shell 8 are held normally firmly togetherby a layer 10 o f solder, which is interposed between the same. The solder composing this layer 10 is obviously a heat-susceptible device formed of the fusible or softenable material which can be affected by the heat concentrated by a heat-concentrating device. In the interior of the shell 9 is arranged a plug 11, having a central bore in which is arranged a small stick or piece 13 of common graphite-such as is used, for example, in lead-pencils. The plug 11 is made of insulating material-such, for example, as vulcanite or hard rubber. The lower end of the carbon rests upon the bottom of the inner shell 9. The stick of raphite' 13 extends up above the top of the p ug 11. The releasing device C thus constructed is inserted in an opening inthe upper cross-piece 4 of the circuit-breaking device B, this opening being sufficiently large to receive the shell 8 but too small to receive the flaring or expandei end of the inner shell 9. In this way the device C serves as an anchor for the link 7, the outer shell 8 being conveniently provided with an eye ,adapte-fl to receive the up'- per end of the link 7. When thus mounted in the circuit-breaking device B, a metallic strip 14 is held by suitable thumb-screws at the top of one of the rods 3 and extended across'from that rod, so asto rest upon thetop of the graphite .stick 13. The strip 14 serves not only to make connection between the rod 3 and the stick 13, but also serves to hold thesticki 13 against the bottom of the inner shell 9. Another metallic strip 15 is extended from the other rod 3 to the device C and is conveniently arranged below the outwardly-flaring part of the inner shell 9, this strip 15 being alsol connected with the rod 3 by suitable binding-screws thereon.

In this way the circuit is closed through each circuit-breaking device B 4by means of the rods 3 3,'the strips 14 and 15, the graphite stick 13, and' the mnershell 9.

The operation of the device is as follows:

When an unduly strong current passes` through the circuit, the carbon stick '13 is heated. thereby to such an extent as to cause the solder'l() to become softened. As soon as it is softened the shell 8 is free to leave the inner shell9, and consequently the springsV 6 6 arel free to operate. They therefore operate, and in so doing they orce the crosspiece 4 rapidly'upward, thereby withdrawing the rods 3v 3 from the sockets 1 1 in the base A. The impetus given to the cross-piece 4 is so great that the whole device B springs bodilyaway from the base A a considerable distance', thereby justifying the name jump-out, which is commonly employed for this general form of circuit-breaking device. When one of the circuit-breaking devices B is thus ejected or thus jumps out, a

wide gap is opened in the circuit by the withdrawal of the rods 3 3 from their sockets 1 1.

The form of protector illustrated in Figs. 4, 5, and 6 comprises a base A and a pair of circuit-breaking devices, one for each side of the circuit. Each of these circuit-breaking devices consists of a standard 16, a spring 17, and a releasing device C', supported by said spring and standard and engaged with the upper ends thereof. The releasing device C', as well shown in Fig. 6, consists of a cylinder 18, composed of insulating material, preferably hard rubber or vulcanite; a graphite stick 19, preferably similar in composition to the graphite stick 13, previously referred to; a plug 20 screwed into one end of the cylinder 18 and a plug 21 screwed into the other end;

shaped end 21%, and into this is fitted the correspondingly-shaped nose 22a of a plug 22,

the nose 22a and Haring socket 21a being secured to one another by a layer 23 of solder adapted to be softened by a moderate degreeV of heat. The plugs 20 and 22 are formed with annular recesses, which can be inserted in suitable slots formed in the top of the standard 16 and spring 17, whereby the device C can be held and engaged by said stand-v ard and spring.

The operation of this device, is as follows: As,in the case of the form of protector described before, .the passage f of an unduly strong current heats the graphite stick 19, and in the present form this heat is conveyed to the layer 23 of solder, so that this solder is softened or fused. When thus softened or fused, the flaring end 21a of the plug 21 and i .separation of these two conducting members,

it being understood, of course, that the circuit is made through the standard 16 and spring 17.

As previously stated, these different de- 'vices will serve to illustrate the various ways in which my present invention can be employed g but I do not by any means consider these the only 'applications which can be made of the invention. It will be seen thata protector embodying my present invention, whether it be of the kind illustrated and described here or not, possesses many desirable features, among which are simplicity of construction, cheapness of manufacture, and the dispensing with all wires.

By material of high specific resistance, as used herein, I .mean .materials such as graphite, carbon, and the like, whose s y ecific resistance is so great, as compared wit that of the metals silver, copper, zinc, iron, and the like, that the are not usedcommercially as electrical con uctors and are not, in fact,

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what are considered generally as good conductors. For instance, the specific resistance of silver is .7 7 and for the other metals it is greater," extending up to 64.52 for bismuth. The speciic resistance of graphite, on the other hand, is given by a good authority as 1106 and that of gas-carbon as 2037. It will be seen that the metals form a group whose speciiic resistances do not differ greatly from one another as compared with the specific resistances of graphite and gas-carbon. Hence it will be seenthat the latter materials can be considered high specific-resistance conductors as compared with the metallic conductors, and it is such materials that Ifintend to designate by the term high-resistance conductors, it being seen that theentire group of metals,.even` includ-ing the metals antimony, mercury, and bismuth, ordinarily considered high-'resistance conductors, are, as compared with graphite, carbon, and the like, of low specific resistance. I

Whatl I claim as my invention isk 1. In a protector, the combination of inner and outer shells or casings, the-outer one inclosing the inner one,`a layer of material susceptible to a moderate degree of heat arranged between said :shells vor casings and adapted to securethe same together, and a heat-concentrating device confined within the innershell. l

2. In a protector, the combination of aninner shell and an outer shell inclosing the inner shell, a layer .of solder interposed between said shells and adapted to secure the' same together, and a stick or body of highresistance graphite arranged and conlined within the inner shell and associated therewith so that the heat generated bythe graphyite will act to melt-or soften the-solden 3. In a protector, the combination -oinner and outer shells or casings, the former inclosed within the latter and provided withy an expanded or enlarged upper part, an in-` sulating-plug arranged within'the inner shell,

la layer of solder uniting the shells, anda graphite'stick arran ed within a bore formed. in said insulating-p ug, substantially as set forth.

4. Ina protector, the combination'- of inner and outer shells, the inner shellbeing provided with an enlarged upper portion and theoutershell being constructed with a projection having an eye or aperture, a layer of solderuniting the shells, a plug composed of insulating material varranged within the inner shell, and -a stick of graphite arranged Within the bore formed in the said insulating-plug, substantially as described.-

5. In a protector, the combination with a base having sockets, of a circuit-breaking device comprising a pair of metallic rods adapted to it in the'said sockets of the base, an upper cross-piece fixed upon said rods, a lower cross-piece iitted loosely on said rods, a pair of springs interposed between said crosspieces andtending -to separate the same, a releasing device comprising a couple of separabl'e members, a mass of solder or like material interposed between said members and adapted to hold the same together, a body or stickv of carbon or like material associated with one of said members 'so that the heat generated by the carbon will fuse or soften the solder or like material, the said releasing device being engaged by the upper crosspiece, a link connecting the releasing device and the lower cross-piece and electrical connections whereby the-said body or stick of carbon or lthe like is included in the circuit.

6.--In a protector, the combination with a base having a pairof sockets, of a circuitbreaking device consisting of a pair of metallic rods adapted to fit in said sockets, an upper cross-piece rigidly secured to the upper ends of said rods, a lower cross-piece arranged to slide upon the lower portions ofthe same, a pair of springs interposed between said cross-pieces andl tending normally vto separate the same, a releasing device consisting of inner and outer metallic shells, the inner shell having an enlarged upper end, a layer of solder interposed between said shells and adapted to hold the same normally together, a stick'or body of carbon arranged within `the vinner shell, a plug of insulating materiall also arranged within the inner shell and serving to -holdthe vcarbon in position, the said releasing device being arranged in an aperture'in the-upper cross-piece so that the y enlargedportionl of the inner shell of said device engages the said cross-piece, a link engaging the outer shell of the releasing device and- 4secured to the lower loosely-mounted cross-piece, a conductor connecting one of said metallic rods with one of the shells of the releasing device, and a metallic strip extended from the other rod over to the top of the carbon in the plug ofthe releasing device andarranged upon said carbon lso as to make contact therewith and force the carbon against the bottom of the shell, substantially as described,

'In witness whereof vvI hereunto subscribe my name this 28th day of November, A. D. 1900.

QHARLES A. ROLFE. Witnesses:

A.. MILLEn- BELFIELD, HERBERT F. OBERGFELL.

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